Noise is emerging as both an economic and public policy issue. Soundproof rooms are required for a variety of purposes. For example, apartments, hotels and schools all require rooms with walls, ceilings and floors that minimize the transmission of sound thereby to avoid annoying people in adjacent rooms. Soundproofing is particularly important in buildings adjacent to public transportation, such as highways, airports and railroad lines, as well as in theaters, home theaters, music practice rooms, recording studios and others. One measure of the severity of the problem is the widespread emergence of city building ordinances that specify a minimum Sound Transmission Class (“STC”) rating. Another measure is the broad emergence of litigation between homeowners and builders over the issue of unacceptable noise. To the detriment of the U.S. economy, both problems have resulted in major builders refusing to build homes, condos and apartments in certain municipalities; and in widespread cancellation of liability insurance for builders.
In the past, walls typically were made up of studs with drywall on both exterior surfaces of the studs and baffles or plates commonly placed between the studs in an attempt to reduce the transmission of sound from one room to the next. Unfortunately, even the best of such walls using standard drywall are capable of only reducing sound transmission by approximately 30 db, and much of that is focused on mid-range and high frequencies rather than lower frequencies which cause most of the complaints and litigation.
Various techniques and products have emerged to abate this problem, such as: replacement of wooden studs by steel studs; resilient channels to offset and isolate drywall panels from studs; mass-loaded vinyl barriers; cellulose sound boards; cellulose and fiberglass batt insulation; and techniques such as staggered-beam and double-beam construction. All help reduce the transmission of noise, but, again, not to such an extent that certain sounds (e.g., lower frequencies, high decibel) in a given room are prevented from being transmitted to an adjacent room, including rooms above or below. A brief review of commercially available products shows that there has been little innovation in these techniques and technologies for many years.
Accordingly, what is needed is a new material and a new method of construction to reduce the transmission of sound from a given room to an adjacent room.